For whatever reason I find that seeing gaps in IDs between VMs annoying. I don't like seeing gaps such as:

VM100 - 100
VM101 - 101
VM103 - 103
VM104 - 104

Thankfully there's a bit of a way to adjust the IDs for VMs. I would recommend taking a backup of the VM and it's configuration file(s) beforehand. Once you're ready you can run the following command to display information about your logical volumes.

lvs -a

This should display something similar to:

  LV              VG   Attr       LSize   Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  vm-100-disk-0   data -wi-ao---- 120.00g                                                    
  vm-101-disk-0   data -wi-ao----  80.00g                                                    
  vm-101-disk-1   data -wi-ao---- 120.00g                                                    
  vm-102-disk-0   data -wi-a----- 120.00g                                                    
  vm-103-disk-0   data -wi-ao----  80.00g                                                    
  vm-104-disk-0   data -wi-ao----  80.00g                                                    
  vm-105-disk-0   data -wi-ao---- 320.00g                                                    
  vm-105-disk-1   data -wi-ao---- 120.00g                                                    
  vm-105-disk-2   data -wi-ao---- 120.00g                                                    
  vm-106-disk-0   data -wi-ao----  80.00g                                                    
  vm-107-disk-0   data -wi-ao---- 120.00g                                                    
  data            pve  twi-a-tz--  59.66g             0.00   1.59                            
  [data_tdata]    pve  Twi-ao----  59.66g                                                    
  [data_tmeta]    pve  ewi-ao----   1.00g                                                    
  [lvol0_pmspare] pve  ewi-------   1.00g                                                    
  root            pve  -wi-ao----  27.75g                                                    
  swap            pve  -wi-ao----   8.00g 

Next, determine which VM you're wanting to change the ID of. In the following commands I will be changing the VM ID of 101 to 100.

This command will update the name of the logical volume:

lvrename data/vm-101-disk-0 vm-100-disk-0

Next we want to update the ID in the VMs configuration file:

sed -i "s/101/100/g" /etc/pve/qemu-server/101.conf

After that we want to rename the VMs configuration file:

mv /etc/pve/qemu-server/101.conf /etc/pve/qemu-server/100.conf

Once those commands have been run you can start the VM up again.